Liners for shredding machines

ABSTRACT

A manganese steel liner for a reducing machine has antipeening slots opening out of the working surface thereof. When the metal of the liner experiences plastic flow at the working surface as a result of reduced fragments impinging against the working surface, the metal will flow into the slots without creating excessive stresses in or substantial deformation of the liner.

ited States Patent 1 Miller 1 Nov. 11, 1975 1 LINERS FOR SHREDDINGMACHINES [75] Inventor: Donald G. Miller, Glendale, Mo.

[73] Assignee: American Pulverizer Company, St.

Louis, Mo.

22 Filed: Apr. 7, 1974 211 Appl. No.: 456,464

[52] US. Cl. 241/189 R; 241/285 A [51] llnt. Cl. B02C 13/09 [58] lFieldof Search 241/189 R. 207, 285 A [56] References Cited UNITED STATESPATENTS 2185331 1/1940 Conway 241/189 R X 2463.223 3/1949 Verch 241/189R X 3.6231174 11/1971 Alt 241/189 R Strom 241/189 R X Mertz 241/207Primary ExuniinerGranvi11e Y. Custer. Jr. Assistant Erumz'ner-Howard N.Goldberg Artur/zen Agent. or Firm-Gravely, Lieder Woodruff [57] ABSTRACTA manganese steel liner for a reducing machine has antipeening slotsopening out of the working surface thereof. When the metal of the linerexperiences plastic flow at the working surface as a result of reducedfragments impinging against the working surface. the metal will flowinto the slots without creating excessive stresses in or substantialdeformation of the liner.

5 Claims, 6 Drawing Figures LINERS FOR SHREDDING MACHINES BACKGROUND OFTHE INVENTION This invention relates in general to reducing machines andmore particularly to liners for reducing machines.

The typical metal shredding machine has a housing and a rotor whichrevolves in the housing. Scrap metal is fed into the housing and torninto small fragments by hammers on the rotor. The rotor imparts highvelocities to these fragments and to prevent the fragments from.damaging the housing walls. the walls are protected with replaceableliners. I

The most commonly used liner material is manganese steel, and when castinto relatively thin plates this material is ideally suited for use inrelatively small ma chines such those used to shred steel turnings.metal cans, sheet metal or aluminum castings. In particular. manganesesteel is extremely tough and can withstand high impacts withoutcracking. Also, the metal fragments impinging against the liner coldwork it and in so doing create plastic flow. This tends to harden thesteel at its exposed surface. leaving the liner with a hard workingsurface and a tough core. Thus. the rate of wear decreases with use.

The work hardening characteristics of manganese steel createdifficulties where that steel is used in extremely thick liners, such asthose required for large shredders capable of shredding automobiles.appliances, and the like, due to the extremely large amount of plasticflow. Indeed, the stressesset up within the top 2 to 3 inches of suchcasting may actually cause the top 2 to 3 inches to separate from therest of the liner. Moreover, the surface peens or mushrooms over itsedges, but the edges are usually confined quit e closely, so as a resultthe casting bows inwardly towardthe rotor. This in turn contributes tocracking and" also causes the bolts which hold the liner against thehousing to fail.

SUMMARY OF THE INVENTION One of the principal objects of the presentinvention is to provide a manganese steel liner which can withstandsevere impacts without failing. Another object is to provide a liner ofthe type stated which may beused in extremely thick configurations inheavy duty shredding machines. A further object is to provide a liner ofthe type stated which will not undergo a substantial increase in widthwhen subjected to severe impacts. Still another object is to provide aliner of the type stated which is ideally suited for use in shreddingmachines capable of reducing automobiles, appliances. andother largemetal objects. These and other objects and advantages will becomeapparent hereinafter.

The present invention is embodied in a liner having voids opening out ofits working surface. As the rnetal of the liner undergoes plasticdeformation, it flows into the voids. The invention also consists in thepartsand in t the arrangements and combinations of parts herein'af .terdescribed and claimed.

DESCRIPTION or THE DRAWINGS refer to like parts wherever they occur:

FIG. I is a transverse sectional view of a shredder provided with linersconstructed in accordance with and embodying the present invention;

FIG. 2 is a plan view of one of the spout liners in the shredder;

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 2: FIG. 4 isaplan view of a top liner; 7

'FIG. 5 is a sectional view taken along lines 5-5 of FIG. 4; and

FIG. 6 is a plan view of a side liner.

DETAILED DESCRIPTION due to the centrifugal forces on them, normallyproject.

outwardly and define a hammer circle C. Withinthe inlet l0,- the hammercircle C downwardly converges with the front wall 6 of the housing H.Moreover, the hammers 14 move toward the front wall 6 as they pass bythe inlet 10.- At the lower end-of the inlet It the housing H supports agrinding plate 18, and beyond the grinding plate 18 it is provided witha plurality of grates 20 having openings through which shredded materialis discharged. The grinding plate 18, and the grates 2010-.

gether occupy an are which extends about 180 along the hammer circle C.

The metal or other material to be shredded is intro-,

duced into the housing H through the inlet, 10. and as the hammers 14pass by the inlet 10, they tear fragments from the scrap. Thesefragments are reduced still further along. the grinding plate 18 andgrate 20. Most of the fragments are discharged through the openings.

in the grate 20, leaving the grate 20 at a high velocity. However, someof the fragments. particularly the oversized ones, are carried beyondthe grate and hurled wit-h great velocity toward the top wall 8 of thehousing H.

To prevent the scrap from damaging the housing I-I due to high forcesappliedto it at the inlet 10, the front wall 6 at the inlet I0 iscovered with spout liners 30.

Likewise, to protect the top wall 8 from the severe impactsof thefragments propelled upwardly beyond the grate 20, the top wall 8 iscovered with top liners 32. Also, the sidewalls 2 are protected withside liners 34, 35, 36 and37. The liners 30, 32 34 and 36 are held inplace with bolts 38.

All of the liners 30, 3 2, 34, 35, 36 and 37 are castings with the castmetal being known as manganese steel.

The specific designation for standard austenitic manganese steel with amanganese content of from I 1 to 14 percent'manganese and about Ipercent carbon is A- l28-64, and is commonly referred to as HadfieldManganese steel, or simply, manganese steel. Some specific alloys aremade with small amounts of chrome and/or molybdenum and may also beknown as chrom-manganese steel or moly-manganese steel or MOL.

The spout liners 30 which are located in the inlet 10 (FIGS. 2 and 3)are representative of the liners 30, 32, I 34, 35, 36 and 37. Each spoutliner 30 extends the width of the front wall 6 and has a working surface40 presented toward the rotor R. The liner 30 is further provided withbolt holes 42 for receiving the bolts 38. Actually. the holes 42 areeounterbored from the working surface 40 so that the heads of the bolts38 are set as close to the front wall 6 as possible. In addition. theliner 30 has antipeening grooves or slots 44 which open inwardly towardthe rotor R. that is they open out of the working surface 40 which isexposed to the fragments propelled away from the rotor R and resistforces applied to the scrap by the rotor R. The slots 44 are paralleland extend transversely of the liner 30 the full width thereof. Hence,the slots 44 are oriented in the vertical direction. The bolt holes 42are centered between the slots 44.

The depth dofeaeh slot should be between 25 and 50 percent of the totalthickness 1 of the liner 30 with a depth of 33 percent being preferred(FIG. 3). Usually the thickness 1. which is the distance from theworking surface 40 to the major surface area facing the front wall 6 ofthe housing H, is about 7 inches. Mounting bosses and locating ribs areexcluded in measuring the thickness I. The side surfaces of each slot 44are tapered slightly such that they diverge from the bottom of the slot44. whereas the bottom is curved. The slots 44 should be wide enough tooccupy between l and percent of the working surface 40 out of which theyopen. In other words. if the width of the liner is W and its length isl. the area of the outwardly opening ends of the slots 44 should be l5to 25 percent of (w A I). The volume occupied by the slots 44 should bebetween 3 and 7 percent of the total volume of the liner 20 and shouldpreferably be 5 percent. The area of the working surface 40 between anytwo adjacent slots 44 should not exceed 400 in. and should preferably bebetween IOO in. and 250 in, including the area of the bolt holes 42.

Wider liners such as the top liners 32 (FIGS. 4 and 5) in addition tothe transverse antipeening slots 44, may be provided with longitudinalslots 46. The longitudinal slot 46 of each top liner 32 extends the fulllength of the liner 32 and possesses the same depth and cross sectionalconfiguration as the transverse slots 42. The top liners 32 are alsoabout 7 inches thick.

Where a liner is quite wide. such as the side liners 34, 35, or 36 (FIG.6), it should have a plurality of both transverse antipeening slots 44and longitudinal antipeening slots 46 which intersect and form a gridpattern. The top side liners 34, 35 and 37 are about 2 inches thick.

In use. the liners 30, 32, 34, 35, 36 and 37 do not develop stressessevere enough to cause the metal near the working surface to break awayfrom the core metal, nor do they undergo substantial deformation. Thus.they have a much longer service life. In particular, when the metalofthe liner 30 tends to flow as a result of being subjected to theforces applied by the scrap when acted upon by the rotor R, the flow isinto the antipeening slots 44. The flow from adjacent areas maygradually fill the slots 44, but the work hardened metal at the workingsurface 40 still retains its continuity with the core of the liner 30which is the portion adjacent the front wall 6. Moreover. the liner 30does not experience any significant tendency to lengthen, and as aresult it does not bow toward the rotor R. This in turn keeps the bolts38 in tact. The liners 32, 34, 35 and 37 function in the same manner,only the metal at the 4 working surface 40 can flow into thelongitudinal slots 46 also. w g a Generally speaking the antipeeningslots in the liners heed not form any pattern. The antipeening slotsshould however I. open toward the direction from which the fragmentscome or impact forces are applied so that they open out of the workingsurface area against which the fragments impinge;

2. having a depth between 25 and 50 percent of the thickness of theliner:

3. border or enclose a portion of the working surface not less than 50in. and not greater than 400 inF;

4v occupy between 3 and 7 percent of the total volume of the liner;

5 occupy between 15 and 25 percent of the working surface out of whichthey open.

In measuring the thickness of a liner small mounting bosses, peripheralribs, and similar protrusions from the major surface area at the back ofthe liner should not be considered Likewise. shallow recesses openingout of the back of the liner should not be computed. Thus, the thicknessis the distance from the major surface area at the rear of the liner tothe working surface 40. In computing thetotal area of the workingsurface. the areas of the outwardly opening ends of the slots 44 and 46and of the bolt holes 42 should be included. In other words. the areaofthe working surface on a rectangular liner is for all intents andpurposes its length times its width. In computing the surface areabordered or en- 7 closed by two or more slots. the areas of the boltholes are included in that surface area,

This invention is intended to cover all changes and modifications of theexample of the invention herein chosen for purposes ofthe disclosurewhich do not constitute departures from the spirit and scope of the,invention.

What is claimed is:

1. In a reducing machine including a housing having an inlet. a grate inthe housing, and a rotor which revolves in the housing above the grateand about a horizontal axes so as to engage material introduced into thehousing through the inlet to reduce that material to fragments ofsmaller size which will pass through the grate, the improvementcomprising a liner attached firmly to the housing above the grate andoutwardly from the rotor such that it is between the housing and rotorso as to protect the housing from fragments propelled by the rotor, theliner being formed from steel which tends to flow upon being subjectedto impacts and having a working surface presented toward the rotor, theliner further having a plurality of grooves which open out of theworking surface, the grooves having curved inner ends and further beingtapered outwardly from their curved inner ends so that the grooves havetheir greatest width at the working surface, the depth of each groovebeing between about 25 and 50 percent of the thickness of the liner atthe groove, and the area bordered by two or more grooves being betweenabout 50 in} and 400 in whereby the metal of the liner will flow intothe grooves asit undergoes plastic deformation and will not createexcessive stresses or substantially deform the liner as a whole.

2. The structure according to claim 1 wherein the volumeof thegr'oove'is between 3 and 7 percent of the .total volume of the liner(groove included). included.

metal from which the lineris formed is manganese 3 T stmcwrc, ording toclaim I wherein h 5. Thc'struct'ure according to claim I wherein thetween about 15 and 25 percent of the total area of the l I t workingsurface for the liner (groove area included in 4. A liner according toclaim 1 wherein the grooves 5 mm] working Surface area);

intersect to form a grid pattern.

steel.

areaof the outwardly opening ends olthe grooves is he-

1. In a reducing machine including a housing having an inlet, a grate inthe housing, and a rotor which revolves in the housing above the grateand about a horizontal axes so as to engage material introduced into thehousing through the inlet to reduce that material to fragments ofsmaller size which will pass through the grate, the improvementcomprising a liner attached firmly to the housing above the grate andoutwardly from the rotor such that it is between the housing and rotorso as to protect the housing from fragments propelled by the rotor, theliner being formed from steel which tends to flow upon being subjectedto impacts and having a working surface presented toward the rotor, theliner further having a plurality of grooves which open out of theworking surface, the grooves having curved inner ends and further beingtapered outwardly from their curved inner ends so that the grooves havetheir greatest width at the working surface, the depth of each groovebeing between about 25 and 50 percent of the thickness of the liner atthe groove, and the area bordered by two or more grooves being betweenabout 50 in.2 and 400 in.2, whereby the metal of the liner will flowinto the grooves as it undergoes plastic deformation and will not createexcessive stresses or substantially deform the liner as a whole.
 2. Thestructure according to claim 1 wherein the volume of the groove isbetween 3 and 7 percent of the total volume of the liner (grooveincluded). included.
 3. The structure according to claim 1 wherein themetal from which the liner is formed is manganese steel.
 4. A lineraccording to claim 1 wherein the grooves intersect to form a gridpattern.
 5. The structure according to claim 1 wherein the area of theoutwardly opening ends of the grooves is between about 15 and 25 percentof the total area of the working surface for the liner (groove areaincluded in total working surface area).